Making torpedo after-bodies.



l. A. STEINMETZ. MAKING TORPEDO AFTER-BODIES.

APPLICATION FILED MAR. l2. HHB- 1,298,81 5. Patented Apr. 1,1919

wwnaoo JOSEPH A. s'rmNME'rz, or PHILADELPHIA, PENNSYLVANIA. v

MAKING TORPEDO AFTER-BODIES.

Application filed March 12, 1918. Serial No. 221,921.

phia and State of Pennsylvania, have mvented certain new and useful Improvements in Making Torpedo After-Bodies and the like, of which the following is a specification, reference being had therein to the accompanying drawing.

lit is desirable to make the after bodies of torpedoes and the like of thin substantially seamless wrought metal. The structure must conform closely to such shape as long and careful study and experiment have shown most desirable, and it has proved difficult to produce perfect bodies of this kind. In the form desired the body is cylindrical at the forward end and diminishes at a gradually varying rate in passing thence toward the rear end, so as to give it a Socalled stream line or fish body form.

The object of this invention is to provide for forming a shell of thin wrought metal which shall have precisely the desired general form, which shall have no part of the metal seriously impaired by spinning or pressing, and which shall be smooth, even, and without buckling at any point.

Carefully rolled sheet metal combines strength with uniformity and low cost, and I have found that by cutting from a plane sheet a blank adapted, when properly rolled so that its edges abut, to form a conical frustum, a highly desirable body of the kind mentioned may be made. To form such body, the blank when rolled as just suggested has its meeting edges united by electrical welding or oxyacetylene fusion, or other known uniting method, and the frustum thus formed is spun down upon a mandrel having the exact shape desired for the shell.

In the accompanying drawings,

Figure 1 is a perspective view of a conical frustum formed by rolling up a sheet metal blank and integrally uniting its edges.

Fig. 2 is an axial section of the frustum when placed upon a suitable form preparatory to spinning or pressing.

Fig. 3 is an end view of the structure of Fig. 2.

In these figures, A represents a rigid mandrel or form externally finished to the exact form desired for the tubular body to be Specification of Letters Patent.

Patented Apr. 1, 1919.

manufactured.- It is cylindrical near its largerend and tapers toward the smaller end-at a gradually increasing rate.

B is a conical frustum of sheet metal integrally united alonga line B", the trustum being of such size that when placed upon the form A with its axis coinciding with the axis of the form it is tangent to the latter near its middle and has its endperipheries approximately equidistant from the corresponding peripheries of the end portions of the form. The frustum or shell is then progressively forced into close contact with the form by spinning or pressing devices moving from the tangent line toward each end, the shell at the completion of the operation having the position indicated in dotted lines 0 in Fig. 2. When completed the shell is removed from the mandrel. As the shell metal is undisturbed at the contact line, very slightly displaced in the central region, and the total end displacement is equally divided between the two ends, the molecular displacement varies from zero in the middle to a small amount at the ends. It follows that very little of the strength of the rolled metal is lost, that the operation is very rapid, and that the resultant shell is substantially perfect in form and quality throughout, being entirely free from weak spots and inequalities, due to incipient buckling or otherwise.

The method involves so little expenditure of time and labor that it is advantageously used for forming bombs of various kinds where exact form is not important, as for example in producing bombs to be dropped from aircraft.

What I claim is:

1. The method of producing hollow thin metal bodies tapered in one direction only and at a gradually increasing rate which consists in using amandrel so tapering, forming from thin ductile metal a conical frustum adapted to fit that portion of the mandrel approximately midway between its ends, when placed thereon with its axis coincident with the axis thereof, applying in wardly directed pressure to the frustum beginning at the circle of contact and passing progressively in opposite directions therefrom, causing the shell to fit the mandrel throughout.

.2. The method of roducing hollow metal bodies of stream line form or which taper at a progressively varying rate which consists of bending sheet metal to conical form, integrally uniting its meeting edges andpressing the conical shell into close contact With a rigid mandrel so tapering haying the same axis and with the portlon approx} inately midway between its ends primarily in contact with the corresponding portion of the shell.- V

3. The method of producing from sheet metal hollow bodies which taper at a progressively ineieasing ratein passing irom one end to the other which consists in using 69min); hi in nt m y e Mmi d 0 .cident, and spinning the end a rigid mandrel thus tapered, rolling a sheet metal blank to frusto-conieal form and integrally uniting its meeting edges to form a shell having approximately midway between its ends aninternal diameter equal to the external diameter of the corresponding portion of said mandrel, placing the shell upon the mandrel With the axes of the two coinportions of the shell-down upon the mandre In testimony whereof I hereunto aflix my signature; v

JOSEPHA {STEIN-METZ.

five cents seem by addressing the Commissiener e1 Patents :1 Washington, ,D. 06 

